In view of several recent incidents, manufacturers of over-the-counter drugs have become concerned that their products be sold in tamper-evident or tamper-resistant packages. The purpose of such security measures is to verify that the container has not been opened and thus that the contents have not been tampered with in some way. The measures must be inexpensive enough to be produced in bulk and should dependably provide a readily apparent indication of tampering.
A low cost seal for a container is provided by gluing paper across its opening. However, it usually is possible to peel off the paper and then reseal it, leaving an appearance quite similar to that of an unopened article.
More sophisticated seals are caps that must be permanently structurally altered in order to be opened, as taught in U.S. Pat. Nos. 3,913,772 (Ochs); 4,446,979 (Goch); 4,457,437 (Heath); and 4,474,304 (Jacobs). Also known are seals which provide visual or audible indication whether a desired vacuum or pressure is intact, as taught in U.S. Pat. Nos. 3,152,711 (Mumford et al.); 3,160,302 (Chaplin); and 3,443,711 (Olson). U.S. Pat. No. 4,480,749 (Lauris et al.), shows thermoplastic seals made secure with temperature indicators.
Tamper-resistance and counterfeit-resistance are also desired for embossed cards, such as credit cards. One frequently encountered form of fraud is the alteration of the embossed characters on a card, thereby changing the account number or expiration date indicated thereon. One security technique commonly used to combat such fraud involves "tipping", i.e., color coating the raised portions of the embossed characters. However, this coating is often easily removed, following which the original characters may be flattened and the card re-embossed with new characters that may then be colored to give the card a genuine appearance. Another common security measure is the use of a material that stress-whitens, such as is seen in labeling strips and some bank and credit cards. Flattening of the raised area may cause the card to revert to its original color, however, and the card may then be stamped with fraudulent information.
There is a need in both the over-the-counter drug industry and in the credit card industry for better counterfeit-resistant security measures to indicate attempted tampering. Such measures should provide a clear, easily read indication of tampering and should be resistant to imitation or duplication designed to circumvent the intended function.